The invention relates to a process for the preparation of a hydrocarbon mixture from a mixtures of carbon monoxide and hydrogen.
Mixtures of carbon monoxide and hydrogen can be converted into hydrocarbon mixtures by using a mixture of two catalysts which has been prepared by dispersing a crystalline metal silicate of a special structure in water together with one or more precipitates in which zinc and one or more metals chosen from chromium, copper and aluminum occur and which precipitates have been prepared by adding a basic reacting substance to one or more aqueous solutions of salts of the metals involved, spray-drying the dispersion thus obtained and calcining the spray-dried material. Said crystalline metal silicates are characterized in that after one hour's calcination in air at 500.degree. C. they have the following properties:
(a) an X-ray powder diffraction pattern in which the four lines mentioned in Table A are the strongest lines, PA0 (b) in which, in addition to SiO.sub.2, one or more oxides of a trivalent metal A chosen from aluminum, iron, gallium, rhodium, chromium and scandium occur, the SiO.sub.2 /A.sub.2 O.sub.3 molar ratio is higher than 10. PA0 (a) the process may be used as the first step of a two-step process in which carbon monoxide and hydrogen present in the reaction product of the first step are contacted--together with other components of said reaction product, if desired--in a second step with a catalyst comprising activity for the conversion of a H.sub.2 /CO mixture into paraffinic hydrocarbons, which metal components have been chosen from the group formed by cobalt, nickel and ruthenium, PA0 (b) the process may be used as the first step in a three-step process in which the first two steps are carried out as stated under (a) and in which the catalyst used in the second step is a zirconium-, titanium- or chromium-promoted cobalt catalyst supported on silica as a carrier, which catalyst has been prepared by impregnation and/or kneading. In this three-step process advantage is taken of the fact that the high-boiling part of the reaction product of the second step can be converted in high yield into middle distillates by a catalytic hydrotreatment.